ENVIRONMENT

Songbird’s disappearance
from Kauai forests
baffles watchers

By Trish Moore
Star-Bulletin

LIHUE -- Bird-watchers on Kauai are pondering the apparent disappearance of the once-common red-billed leiothrix from Kokee forests.

The leiothrix is a small songbird with a melodic tune that eats fruits and bugs and dwells in mountain forests above 3,000 feet. It's a native of several Asian countries and was introduced to Hawaii early this century.

According to an article in the Hawaii Audubon Society's journal Elepaio, the leiothrix quickly established itself on Kauai in 1918, and large flocks were spotted in the 1930s. From then on, though, the population declined equally rapidly and became a rare sight from the 1940s through the 1970s. The songbird hasn't been seen on Kauai since 1974.

On Oahu, too, the species has had ups and downs. It was a common sight on Oahu in the 1950s, but beginning in 1958 its numbers fell dramatically until almost none were spotted in the next two decades, according to the journal. But the population rebounded on Oahu in the mid-1980s and can again be found in most valleys and forested ridges in the Waianae and Koolau mountains.

Tom Telfer, district biologist with the U.S. Fish & Wildlife Service, says dramatic fluctuation in the populations "shows there's a lot of dynamics we just don't understand."

"It's interesting that a well-established introduced bird would just fall off the face of the earth," he said.

There could be a number of reasons: a lack of diversity in the gene pool, a disease the bird isn't immune to or increased competition from other introduced species.

Native bird populations also go through fluctuating periods, Telfer said. For example, scientists can't explain why the puaiohi, or small Kauai thrush, which was extremely rare 30 years ago, seems to have increased in numbers in recent years.

The red-billed leiothrix was generally found in the mountains of Kokee, Anahola and Waialua.

Scientists concede there may be some birds remaining in isolated areas of Kokee and encourage bird-watchers to look for the species.

The leiothrix is most often detected by its melodic song, which can be confused with the songs of the hwamei and white-rumped shama. And its chatter calls are similar to the vocalizations of the elepaio.

"Voices of Hawaii's Birds," an audio companion to "Hawaii's Birds" (Pratt, H.D. 1996) and available through the Hawaii Audubon Society, have recordings of the red-billed leiothrix.